1. Field of the Invention
The present invention relates to an organic light emitting display device and a method for manufacturing the same.
2. Discussion of the Related Art
With the development of multimedia, importance of a flat panel display (FPD) has been increased, whereby various types of flat panel displays such as a liquid crystal display (LCD), a field emission display (FED), and an organic light emitting display device (OLED) have been commercialized.
Of the various types of flat panel displays, the organic light emitting display device is a self-light-emitting device that does not require a back light unit, unlike a liquid crystal display which is not a self-light-emitting device. As a result, the organic light emitting display device has received much attention as a display device that may substitute for the liquid crystal display, owning to advantages of lightweight and thin type, excellent viewing angle, excellent contrast ratio, low power consumption, and fast response speed.
If the organic light emitting display device is exposed to water, its electrode may be damaged, whereby a problem occurs in that a pixel region is not emitted. Accordingly, an encapsulation technique is generally used to prevent water from being externally permeated into the organic light emitting display device. Hereinafter, an organic light emitting display device, to which an encapsulation technique according to the related art is applied, will be described with reference to FIGS. 1A and 1B.
FIG. 1A is a cross-sectional view briefly illustrating an organic light emitting display device to which an encapsulation technique according to the related art is applied.
The organic light emitting display device 10 shown in FIG. 1A includes a first substrate 1 and a second substrate 2 facing the first substrate 1, wherein the first and second substrates 1 and 2 are spaced apart from each other, and their edge portions are sealed through a sealing member 20 and bonded to each other.
In more detail, a driving thin film transistor DTr is formed on the first substrate 1 for each pixel region P, and a first electrode 11, an organic light emitting layer 13, and a second electrode 15, which constitute an organic light emitting diode E, are sequentially formed on the first substrate 1. The first electrode 11 is electrically connected with the driving thin film transistor DTr. In case of the organic light emitting display device shown in FIG. 1A, since the first substrate 1 and the second substrate 2 are sealed by the sealing member 20, water is prevented from being externally permeated thereinto.
However, in a case of the organic light emitting display device shown in FIG. 1A, since a portion between the first substrate 1 and the second substrate 2 is empty and the first and second substrates 1 and 2 are bonded to each other by the sealing member 20 only, the sealing member 20 may be damaged by external impact or the first substrate 1 may adversely be affected by bending of the second substrate 2, whereby a defect may occur in the organic light emitting display device 10.
FIG. 1B is a cross-sectional view briefly illustrating another organic light emitting display device to which an encapsulation technique according to another related art is applied. The organic light emitting display device 10 shown in FIG. 1B includes a first substrate 1 and a second substrate 2 facing the first substrate 1, and a hardening resin 30 is deposited on an entire surface of the first substrate 1. The hardening resin 30 contains a water absorbent 31 for water absorption, The first and second substrates 1 and 2 are completely bonded to each other by the hardening resin 30. In this way, in the organic light emitting display device shown in FIG. 1B, since the hardening resin 30 is deposited on the entire surface of the first substrate 1, water may be prevented from being in the organic light emitting display device 10. Also, since a space between the first substrate 1 and the second substrate 2 is fully filled with the hardening resin 30, the first substrate 1 or the second substrate is not damaged easily even though external force or impact is given to the organic light emitting display device 10.
However, in case of the organic light emitting display device shown in FIG. 1B, if the water absorbent 31 contained in the hardening resin 30 absorbs water, its volume is increased as much as 1.5 times to 2 times, and the water absorbent 31 of which volume is increased increases stress to the hardening resin 30, whereby adhesion with the first substrate 1 or the second substrate 2 is deteriorated.
For this reason, as shown in FIGS. 2A and 2B, a gap 200 between the first substrate 1 and the hardening resin 30 and between the second substrate 2 and the hardening resin 30 occurs. Particularly, separation of the hardening resin 30 from the first substrate occurs due to the gap between the first substrate 1 and the hardening resin 30, whereby a problem occurs in that the organic light emitting diode is damaged as shown in FIG. 2C. As a result, a problem occurs in that water may be permeated into the organic light emitting display device through the damaged area.